1. Field of the Invention
The present invention relates to an optical fiber switch used to the watch of an optical fiber communication system and to a light measuring instrument. In particular, the present invention relates to a multi-circuit optical fiber switch with several hundreds or more of switching circuits which is intended to increase an operating speed, enhance reliability and optical capability, make maintenance and recovery easy, and reduce a size.
2. Description of the Related Art
Papers (B-973), (B-974) and (B-975) which were reported in Electronic Society Meeting of The Institute of Electronics, Information and Communication Engineers held in 1996 proposed a multi-circuit switch having a great many number of switching circuits. FIG. 7, FIG. 8 and FIG. 9 are schematic views explaining the conventional multi-circuit switch, wherein FIG. 7 is a plan view explaining the principle of the multi-circuit switch, FIG. 8 is a front sectional view explaining the principle of the multi-circuit switch shown in FIG. 7 and FIG. 9 is another front sectional view explaining the principle of the multi-circuit switch, likewise. The conventional multi-circuit switch is composed of a linearly moving type multi-circuit switch using optical fibers and lined-up V-shaped-groove arrays.
A necessary number of V-shaped-groove arrays 3, 3 . . . 3 are disposed to the rectangular member 2 of a fixed side optical fiber assembly and processed at right angles to the longitudinal direction of the rectangular member 2. Fixed side optical fiber cables 8, 8 . . . 8 are bonded and fixed to the rectangular member 2 so that the optical fibers 1, 1 . . . 1 at the extreme ends of the optical fiber cables 8 are lined up in the V-shaped-groove arrays 3. A screw rod 4 of a movable side optical fiber assembly is driven by a not shown stepping motor. A screw hole 5 is formed to a slide block 7 so that it is meshed and engaged with the screw rod 4. The extreme end of a movable side optical fiber cable 9 and the extreme ends of the optical fibers 6 at the extreme ends of the optical fiber cables 8 are projected from the slide block 7 and fixed thereto.
FIG. 8 shows a state that the movable side optical fiber 6 is connected to the fixed side optical fiber 1. The slide block 7 is slightly rotated in the direction of an arrow (clockwise) by a not shown actuator to thereby press the movable side optical fiber 6 against a V-shaped groove 3 and they are connected to each other while matching optical axes of the movable side optical fiber 6 and the fixed side optical fiber 1. FIG. 9 shows a state that the movable side optical fiber 6 is disconnected from the fixed side optical fiber 1. The slide block 7 is slightly rotated by the not shown actuator in the direction of an arrow (counterclockwise) to thereby displace upward and move the movable side optical fiber 6 from the V-shaped groove 3.
The conventional switch proposes to selectively connect many circuits and the optical fiber switch is arranged as a linearly moving type switch using the optical fibers and the lined-up V-shaped-groove arrays. However, there are many drawbacks to practically use the multi-circuit switch.
A first drawback is that the optical fibers are liable to be broken because they have a very thin diameter of 0.125 mm.
A second drawback is that it is difficult to cause the extreme end of the movable side optical fiber to come into intimate contact with the V-shaped groove only by the bending force of the movable side optical fiber. Further, the absolute value of insertion loss and the dispersion thereof are liable to increase because it is difficult to prevent the deposition of dust in the V-shaped groove. This fact has been confirmed by the experiment executed by the inventors of the present invention.
A third drawback is that if, for example, 1.times.400 switches are arranged by disposing 8-wire ribbon optical fibers at intervals of 3.2 mm in the arrangement of a multi-circuit switch, a length of 160 mm is required only by the section where the V-shaped grooves of a fixed side optical fiber mounting plate are formed. Thus, it is impossible to reduce the size of an optical fiber switch.
A fourth drawback is that when there is a difference between the coefficients of linear thermal expansion of the rectangular member 2 for mounting the fixed side optical fibers and the screw rod 4 or when these components are placed in environments having a different temperature, an amount of positional displacement between the V-shaped groove and the movable side optical fiber is increased and an increase in the number of circuits makes the positional displacement more remarkable. As a result, there is a possibility that the movable side optical fiber cannot be accurately guided into the V-shaped groove and is broken by strain.
A fifth drawback is that since the slide block 7 is driven by the screw rod 4 which is driven by the stepping motor, the operation speed of the slide block 7 cannot be made so fast. When for example, the diameter of the screw rod 4 is 6 mm and the screw pitch thereof is 1 mm, the stepping motor must make 160 revolutions to move the slide block 7 by 160 mm. Many of stepping motors used for the above purpose require 500 pulses to make one revolution. If it is supposed that the number of input control pulses is 4000 pulses/sec. when this type of the motor is used, the stepping motor makes 8 revolutions per second. As a result, 20 seconds are necessary to cause the stepping motor to make 160 revolutions even if a motor accelerating and decelerating times are not taken into consideration. Accordingly, the stepping motor is not suitable for the application which requires a high speed operation.
A sixth drawback is that in the linearly moving type multi-circuit switch which employs the optical fibers and the lined-up V-shaped arrays, there is increased probability that the optical fibers are partially broken. Therefore, the optical fibers must be replaced and repaired. However, the replacement and repair of fixed side ribbon optical fibers are not easy, although the movable side ribbon optical fibers can be relatively easily replaced and repaired.
The linearly moving type multi-circuit switch using the optical fibers and the lined-up V-groove-shaped arrays designed based on the conventional idea has problems in reliability as described above and there are many technical problems to be solved to practically use the switch. Accordingly, there has been desired to realize a multi-circuit optical fiber switch of high reliability which is designed based on a novel idea.
It is an object of the present invention to solve the problems of the conventional multi-circuit optical fiber switch described above and provide a multi-circuit optical fiber switch designed by a novel idea which has an increased operational speed, enhanced reliability and optical capability and a reduced size and can be easily maintained and repaired.
It is another object of the present invention to provide an optical fiber switch which has ferrules with fixed side optical fibers and lined-up sleeves disposed on X-Y rectilinear coordinates as well as can be driven in X- and Y-axis directions simultaneously by means of two-dimensional X-Y slide blocks which are driven in X- and Y-axis directions by stepping motors.
It is still another object of the present invention to provide a multi-circuit optical fiber switch of high reliability which is arranged such that a ferrule with a movable side optical fiber is attached to an actuator driven in a Z-axis direction and selectively inserted into a lined-up sleeve located at an arbitrary coordinate position so that it can be connected a ferrule with a fixed side optical fiber inserted into the lined-up sleeve.
It is a further object of the present invention to provide a multi-circuit optical fiber switch of high reliability which uses, as its basic components, ferrules with optical fibers and lined-up sleeves, which have been used as a part of an APC (angled physical contact) optical connector having been completed to a high technical level, and has a connecting capability as high as that of the APC optical connector. It should be noted that the term "physical contact" means to contact physically and thus the apex of the optical fiber in the APC is polished to an inclined spherical shape.
To this end, according to one aspect of the present invention, there is provided a multi-circuit optical fiber switch, comprising a fixed side ferrule assembly composed of a multiplicity of lined-up sleeves, a fixed side ferrule support member for two-dimensionally disposing the sleeves on an X-Y plane and supporting them and a multiplicity of fixed side optical fiber ferrules inserted into the lined-up sleeves and supported thereby, and a movable side ferrule assembly for supporting a movable side optical fiber ferrule and relatively two-dimensionally moving it on the X-Y plane with respect to the fixed side ferrule assembly as well as moving it in a direction (Z-direction) orthogonal to the X-Y plane by a Z-direction drive mechanism to thereby move the movable side optical fiber ferrule to an arbitrary sleeve of the fixed side ferrule assembly so that it can be attached thereto and detached therefrom.
A multi-circuit optical fiber switch, wherein the fixed side ferrule support member is composed of a flat plate member, stepped holes are formed to the flat surface member in the numbers of M (M=1, 2 . . . ) and N (N=1, 2 . . . ) in the lateral (X) direction and the longitudinal (Y) direction of the surface of the flat plate member so that they are orthogonal in the lateral direction and the longitudinal direction and the fixed side optical fiber ferrules are detachably inserted into the lined-up sleeves disposed to the respective stepped holes and fixed therein, and the movable side ferrule assembly comprises a coupling plate having a pair of X-axis slide blocks driven by a first stepping motor on a pair of slide rails disposed on the back surface of the fixed side ferrule mounting plate assembly along the lateral (X) direction in parallel therewith, X-, Y-direction slide table assembly composed of a Y-axis slide block driven by a second stepping motor on a slide rail mounted on the coupling plate at right angles in the longitudinal (Y) direction, and a Z-direction drive mechanism mounted on the Y-axis slide block and reciprocating in a Z-direction, whereby the multi-circuit optical fiber switch is arranged as a 1.times.(M.times.N) orthogonally-disposed-type switch.
A multi-circuit optical fiber switch, wherein the first stepping motor and the second stepping motor can be driven at the same time to thereby cause the movable side optical fiber ferrule to correspond to the arbitrary fixed side optical fiber ferrule.
A multi-circuit optical fiber switch, wherein the X-axis slide blocks of the orthogonally-disposed-type optical fiber switch is driven by the power transmission made by the mesh between a gear disposed to the shaft of the first stepping motor mounted on the coupling plate and meshed and a linear-tooth-shaped rack disposed to the fixed side ferrule mounting plate assembly and the Y-axis slide table is driven by the power transmission made by the mesh between a gear disposed to the shaft of the second stepping motor mounted on the coupling plate and a linear-tooth-shaped rack disposed to the Y-axis slide block.
An L.times.(M.times.N) orthogonally-disposed-type multi-circuit optical fiber switch, wherein a plurality of the movable side ferrule assemblies (L.gtoreq.2) are simultaneously used and the respective ones of the assemblies are caused to correspond to L (M.times.N) pieces of the fixed side ferrules so that the movable side optical fibers can be simultaneously connected to the fixed side optical fibers.
A multi-circuit optical fiber switch, wherein the Z-direction drive mechanism reciprocating in the Z-direction is composed of a latching solenoid for reciprocating an actuator rod by switching the polarity of a current.
A multi-circuit optical fiber switch, wherein the extreme end surfaces of the respective fixed side ferrules and movable side ferrules of the orthogonally-disposed-type optical fiber switch are polished to inclined spherical surfaces having an inclined angle of 4.degree. or more with respect to a surface orthogonal to an optical axis.